What If We Never Find It?:CBS/AP: "Ten days after Malaysia Airlines Flight 370 disappeared with 239 people aboard, an exhaustive international search has produced no sign of the Boeing 777, raising an unsettling question: What if the airplane is never found? Such an outcome, while considered unlikely by many experts, would certainly torment the families of those missing. It would also flummox the airline industry, which will struggle to learn lessons from the incident if it doesn't know what happened. While rare nowadays, history is not short of such mysteries—from the most famous of all, American aviator [Amelia] Earhart, to planes and ships disappearing in the so-called Bermuda Triangle. ... Experts say the plane's disappearance will likely put pressure on airlines and governments to improve the way they monitor planes, including handoff procedures between countries. Flight 370 vanished after it signed off with Malaysian air-traffic controllers, and never made contact with their Vietnamese counterparts as it should have. And if the plane is never found, liability issues will be a huge headache for courts. With no wreckage, it would be difficult to determine whether the airline, manufacturers or other parties should bear the brunt of responsibility."

The Size of the Search: Associated Press: "The search for the aircraft is among the largest in aviation history. The U.S. Navy said P-3 and P-8 surveillance aircraft were methodically sweeping over swaths of ocean, known as 'mowing the grass,' while using radar to detect any debris in the water and high-resolution cameras to snap images. Australian and Indonesian planes and ships are searching waters to the south of Indonesia's Sumatra Island all the way down to the southern reaches of the Indian Ocean. [Huang Huikang, China's ambassador to Malaysia] said China had begun searching for the plane in its territory, but gave no details. ... China also was sending ships to the Indian Ocean, where they will search 300,000 square kilometers (186,000 square miles) of sea. The area being covered by the Australians is even bigger — 600,000 square kilometers (232,000 square miles) — and will take weeks to search thoroughly, said John Young, manager of Australian Maritime Safety Authority's emergency response division."

It's Tuesday, March 18th, welcome to the Slatest PM. Follow your afternoon host on Twitter at @JoshVoorhees, and the whole team at @Slatest.

Putin Welcomes Crimea:Reuters: "Defying Ukrainian protests and Western sanctions, Russian President Vladimir Putin signed a treaty in Moscow on Tuesday making Crimea part of Russia again but said he did not plan to seize any other regions of Ukraine. On the peninsula, a Ukrainian serviceman was killed when a base still held by Kiev came under attack in the main town of Simferopol, the first death in Crimea from a military clash since Russia seized control three weeks ago. Kiev said the attackers had been wearing Russian military uniforms and responded by authorizing its soldiers in Crimea to use weapons to protect their lives, reversing previous orders that they should avoid using arms against attack. In a fiercely patriotic address to a joint session of parliament in the Kremlin, punctuated by standing ovations, cheers and tears, Putin said Crimea's disputed referendum vote on Sunday, held under Russian military occupation, had shown the overwhelming will of the people to be reunited with Russia."

The NSA's DVR: Washington Post: "The National Security Agency has built a surveillance system capable of recording '100 percent' of a foreign country’s telephone calls, enabling the agency to rewind and review conversations as long as a month after they take place, according to people with direct knowledge of the effort and documents supplied by former contractor Edward Snowden. A senior manager for the program compares it to a time machine — one that can replay the voices from any call without requiring that a person be identified in advance for surveillance. The voice interception program, called MYSTIC, began in 2009. Its RETRO tool, short for 'retrospective retrieval,' and related projects reached full capacity against the first target nation in 2011. Planning documents two years later anticipated similar operations elsewhere."

News Chopper Crashes Near Space Needle: Seattle Times: "A veteran Seattle photojournalist and a pilot were killed this morning when a KOMO-TV helicopter crashed onto a street outside Fisher Plaza, just south of the Space Needle. A driver whose car was struck was injured when his car exploded in a fireball. KOMO-TV identified one of those killed as Bill Strothman, 62, of Bothell, a longtime station photographer who worked as a contractor for KOMO. The station identified the pilot as Gary Pfitzner, 59, of Issaquah, also a contractor. ... The helicopter, which apparently was taking off around 7:40 a.m., dropped to the ground, landing on the car that burst into flames on Broad Street. A second car and a pickup were on fire when firefighters arrived, but it isn’t clear if they had been hit by the helicopter or ignited by the fuel, according to the Fire Department."

GM's Recall: New York Times: "General Motors’ chief executive, Mary T. Barra, said Tuesday that she first learned in late December that internal safety committees were analyzing defects in the Chevrolet Cobalt, more than a month before the company decided to issue a huge recall. In her first comments to reporters since the recall, Ms. Barra said that she 'was aware' of an analysis of the safety problems in the Cobalt and other small cars, but did not learn that a recall had been ordered until Jan. 31. G.M. announced its first recall of 778,000 Cobalts and other small cars for defective ignition switches on Feb. 13, and later expanded the safety action to 1.6 million vehicles. 'I was aware there was an analysis going on with the Cobalt,' said Ms. Barra, who at the time was G.M.'s head of product development. But she said she did not know details of the internal investigation until Jan. 31 — the same day that two committees concluded the company needed to recall vehicles because faulty switches could cut off engine power and disable air bags."